# wolfssl-wolfcrypt crate
The `wolfssl-wolfcrypt` crate is a Rust wrapper for the wolfCrypt cryptographic
algorithms portion of the wolfSSL C library.
This crate requires wolfSSL version 5.9.0 or newer.
The crate uses `no_std` so that no Rust standard library is required.
This makes it well-suited for embedded/bare-metal environments.
There is an optional `alloc` feature that enables APIs which require heap
allocation.
## Installation
The `wolfssl` C library must be installed to be used by the Rust crate.
The `wolfssl-wolfcrypt` crate can be used by including it as a dependency in
your project's `Cargo.toml` file.
For example:
```
[dependencies]
wolfssl-wolfcrypt = "2.0"
```
## API Coverage
This crate provides a wrapper API for the following wolfCrypt C library
functionality:
* AES
* CBC, CCM, CFB, CTR, EAX, ECB, GCM, OFB, XTS
* BLAKE2
* CMAC
* ChaCha20-Poly1305
* Curve25519
* DH
* ECC
* Ed25519
* Ed448
* HKDF
* HMAC
* LMS
* ML-DSA
* ML-KEM
* PBKDF2
* PKCS #12 PBKDF
* PRF
* RNG
* RSA
* scrypt
* SHA
* SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3-224, SHA3-256, SHA3-384,
SHA3-512, SHAKE128, SHAKE256
* SRTP/SRTCP KDF
* SSH KDF
* TLSv1.3 HKDF
## RustCrypto Trait Support
In addition to its native API, this crate can implement the common
[RustCrypto](https://github.com/RustCrypto) traits for wolfCrypt-backed types.
Each set of trait implementations is gated behind a Cargo feature so that
projects only pull in the dependencies they need. All features are off by
default.
| `digest` | `digest` | SHA (sha_digest), BLAKE2 (blake2_digest) |
| `mac` | `digest` (mac) | HMAC (hmac_mac), CMAC (cmac_mac), BLAKE2 (blake2_mac) |
| `signature` | `signature` | ECDSA (ecdsa), RSA PKCS#1 v1.5 (rsa_pkcs1v15) |
| `cipher` | `cipher` | AES (aes) |
| `aead` | `aead` | AES-GCM/CCM/EAX (aes), ChaCha20-Poly1305 |
| `rand_core` | `rand_core` | RNG (random) |
| `kem` | `kem` | ML-KEM (mlkem_kem) |
| `password-hash` | `password-hash` | PBKDF2 (pbkdf2_password_hash), scrypt (scrypt_password_hash) |
The BLAKE2, CMAC, and HMAC trait modules additionally require the corresponding
algorithm support to be enabled in the wolfSSL C library.
Enable features in your `Cargo.toml`, for example:
```
[dependencies]
wolfssl-wolfcrypt = { version = "2.0", features = ["digest", "signature"] }
```
## Build Notes
### WOLFSSL_PREFIX
If the wolfSSL C library is not installed in a default location, you can
specify the installation prefix with the `WOLFSSL_PREFIX` environment variable
when building the `wolfssl-wolfcrypt` crate.
For example:
```
WOLFSSL_PREFIX=/opt/my-wolfssl-build cargo build
```
### Cross-Compiling
Ensure that the target you want to build for is installed for Rust.
For example:
```
rustup target add riscv64imac-unknown-none-elf
```
Build with the `--target` option if building manually:
```
export WOLFSSL_PREFIX=/opt/wolfssl-riscv64
cargo build --target riscv64imac-unknown-none-elf
```
To specify the linker for the target:
```
export CARGO_TARGET_RISCV64IMAC_UNKNOWN_NONE_ELF_LINKER=riscv64-elf-gcc
```